In order to identify you, you will be asked to connect with your Twitch account.
While Twitch's authorization page says this site wants to "view your email address", the site doesn't actually use or store your email address. This is the default message for Twitch API's "user_read" scope, which is needed to get your user ID, username, display name, and avatar URL. All of these are available publicly on Twitch anyway.
To remove this site's access in the future, visit your Connections page on Twitch and disconnect MechaSamutz Web Interface.